Macromolecular Spreading

高分子铺展

• 批准号: 0606086
• 负责人: Sergei Sheiko
• 金额: $ 33万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0606086&HistoricalAwards=false
• 关键词: Macromolecular; Spreading

TECHNICAL SUMMARY: The macroscopic behavior of polymer fluids during spreading on solid surfaces is well understood, yet our understanding of the molecular mechanism of spreading remains incomplete and controversial. This lack of microscopic knowledge is now an urgent problem limiting developments in various microtechnologies, whose characteristic time and length scales are approaching those of individual molecules. The goal of this program is to achieve a fundamental understanding of the wetting-induced changes in the dynamics, conformation, and chemical structure of surface-confined macromolecules. Specifically, the funded research will focus on (i) the flow-induced molecular diffusion with direct implications to ordering, mixing, and chemical reactions of macromolecules in flow; (ii) the development of molecular sensors for quantitative measurements of the pressure gradient and friction coefficient, which will lead to understanding of the lubrication effect of surface-condensed vapors on the spreading mechanism and flow rate; and finally (iii) the wetting-induced degradation of highly branched macromolecules. The final focus opens an entirely new avenue in the field of reactivity and functioning of adsorbed macromolecules. Preliminary, the Sheiko group has achieved a breakthrough in experimental studies of the flow structure on the molecular scale. Through molecular visualization, it was demonstrated that flowing macromolecules actively responded to variations in the interfacial properties through changes in both their secondary and primary structures. The previous work set the foundation for the development of a new methodology that will open a vast array of opportunities to both study and control the flow in thin films on the scale below 100 nm. NON-TECHNICAL SUMMARY: The flow properties of molecularly thin polymer films impact coatings, composites, microfluidics, and lubrication. This program will advance fundamental understanding of the conformation and dynamics of surface-confined polymer chains and lead to the development of new technologies for controlling flow on molecular length scales. This work will also lead to elucidation of the effect of the polymer architecture on the wetting kinetics. The program will provide interdisciplinary research training for graduate and undergraduate students, since it combines fine polymer chemistry and advanced experimental techniques. One of the strategic goals is to bring molecular visualization to university and high-school classrooms where the ability to see molecules would be invaluable for the teaching of reaction mechanisms and conformation of polymer molecules. Molecular visualization will be added to polymer courses as new laboratory module and also used as a demonstration tool during regular scientific seminars at the local high schools.

技术摘要：聚合物流体在固体表面上铺展过程中的宏观行为已被充分了解，但我们对铺展分子机制的理解仍然不完整且存在争议。微观知识的缺乏现在成为限制各种微技术发展的紧迫问题，其特征时间和长度尺度正在接近单个分子的特征。该项目的目标是对润湿引起的表面限制大分子的动力学、构象和化学结构的变化有一个基本的了解。具体来说，资助的研究将集中在（i）流动诱导的分子扩散，对流动中大分子的排序、混合和化学反应有直接影响； (ii) 开发用于定量测量压力梯度和摩擦系数的分子传感器，这将有助于了解表面冷凝蒸气对扩散机制和流速的润滑作用；最后(iii)润湿引起的高度支化大分子的降解。最后的焦点在吸附大分子的反应性和功能领域开辟了一条全新的途径。初步来看，Sheiko团队在分子尺度流动结构的实验研究方面取得了突破。通过分子可视化，证明流动大分子通过二级结构和一级结构的变化积极响应界面特性的变化。之前的工作为开发一种新方法奠定了基础，该方法将为研究和控制 100 nm 以下薄膜中的流动提供大量机会。非技术摘要：分子薄膜的流动特性影响涂层、复合材料、微流体和润滑。该计划将促进对表面限制聚合物链的构象和动力学的基本理解，并导致控制分子长度尺度流动的新技术的开发。这项工作还将阐明聚合物结构对润湿动力学的影响。该项目结合了精细高分子化学和先进的实验技术，将为研究生和本科生提供跨学科研究培训。战略目标之一是将分子可视化引入大学和高中课堂，在这些课堂中，观察分子的能力对于反应机制和聚合物分子构象的教学非常有价值。分子可视化将作为新的实验室模块添加到聚合物课程中，并在当地高中的定期科学研讨会上用作演示工具。